1. Field of the Invention
The present invention relates to a load sensor that measures a load acting in one axial direction.
2. Description of the Related Art
Conventionally, there have been known load sensors for measuring a load (a pressing force) acting in one axial direction (for example, a Z-axis direction in an orthogonal coordinate system). Examples of such load sensors are disclosed in JP-A-61-278719 and in JP-A-2000-214002. A load sensor disclosed in JP-A-61-278719 is configured as a top loading balance using a coil spring as a cushioning member. In this load sensor, a stopper is provided on the bottom of a shaft, and the diameter of a through-hole of a case is adjusted for the shaft, whereby a measure against cases where the load sensor receives an eccentric load or an impact in a direction other than a vertical direction is taken. A load sensor disclosed in JP-A- 2000-214002 is configured so as to detect a load in a wide range by two coil springs and two detection elements each made of a magneto resistance element (MR element).
In the configuration of the load sensor disclosed in JP-A-61-278719, a detector is arranged at a portion different from a portion that displaces in response to a load. Therefore, the load senor becomes large, and it is difficult to reduce the size of the entire load senor. Also, since a pan is configured to be large, a shaft should be formed to be long enough with respect to an eccentric load, this load sensor is not suitable for reducing the overall size.
Also, in the configuration of the load sensor disclosed in JP-A-2000-214002, since the coil springs are configured in two stages, the entire load sensor becomes large. Further, since the load sensor does not have a configuration for preventing an inclination of an axial direction in which a load to be measured acts, the load may not be measured accurately.